Merge branch 'mr/adjust_installation' into 'master'

Adjust installation layout.

See merge request eng/toolchain/gnatcoll-core!163

gprproject/gprbuild.py

@@ -205,7 +205,15 @@ def run(self, args: list[str], **kwargs) -> int:
                 "-f",
                 f"--prefix={final_prefix}",
                 f"--sources-subdir=include/{self.project_name}",
+                # This is required to ensure that we can force reinstallation
+                # on top of an existing installation (incremental build
+                # support.
                 f"--install-name={self.project_name}",
+                # --install-name change default value for lib subdir. Not
+                # passing it would create an additional subdir with the project
+                # name (i.e: lib/NAME/NAME.{relocatable|static}/libNAME.so
+                # instead of lib/NAME.{relocatable|static}/libNAME.so
+                "--lib-subdir=lib",
             ]
             if self.gnatcov:
                 # In gnatcov mode, by default copy the gnatcov runtime in the same